Is Weedkiller Destroying Our Bee Population?

By - November 30, 2018
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About a decade ago, there was a noted die-off of honeybees, which was later termed colony collapse disorder. It was uncertain at the time what was causing this alarming problem. But the cause is becoming clearer.

Newsweek warned in a September 2018 article that glyphosate – the active ingredient in the weed killer Roundup – is killing honeybees.  The news magazine stated that glyphosate destroys ‘so-called good bacteria in the guts of honeybees, making them more prone to infection and possibly death.

The Newsweek article referred to new scientific research from the University of Texas at Austin (UT Austin) that indicates that honey bees that have been exposed to glyphosate lose some of the helpful bacteria in their guts and are more likely to get infections and suffer death from damaging bacteria.

Scientists in the UT Austin study – ‘Glyphosate perturbs the gut microbiota of honey bees’ published in Proceedings of the National Academy of Sciences of the United States of America – argue this is strong evidence that glyphosate is contributing to a decline in the honey bee population around the world. Erick Motta, a graduate student who led the research, said that more effective guidelines for the use of glyphosate are needed, especially regarding how bees are exposed to it.

Right now, guidelines of the US government assume that bees are not harmed by Roundup. Evidence shows this is a shaky assumption at best.

Glyphosate interferes with a vital enzyme that is found in microorganisms and plans but not in animals, the study notes. So it has been assumed for years that glyphosate is nontoxic to animals, including humans and bees. But this new study indicates that by changing the gut microbiome in bees, which is the ecosystem of bacteria that reside in the digestive tract of bees, including ones that protect it from dangerous bacteria, glyphosate can compromise its ability to fight many types of infections.

How UT Austin Bee Study Was Conducted

According to the study, researchers exposed bees to glyphosate at levels that commonly occur in crop fields, yards and on the side of the road. The researchers worked with adult worker bees with established gut communities that were collected from hives at the University of Texas Austin.

They were marked on the thorax with paint, given glyphosate in amounts of 5 or 10 mg/L or sterile sucrose syrup for five days and taken back to the same hive. Fifteen bees from each group were studied before and three days after reintroduction to the hive. The same experiment was done using bees from different hives and different years. DNA was taken from dissected guts and used as a template for a qPCR analysis. DNA samples from the first experiment were used for Illumina sequencing at the Genomic Sequencing and Analysis Facility at UT Austin.

Of the eight major species of healthy bacteria in the bees that were exposed, four were found to be less abundant. The most affected bacterial species was Snodgrassella alvi, which is a vital microbe that assists bees in processing food and defending against various pathogens.

More Details of University of Texas Study

The study noted that glyphosate targets the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) enzyme in the shikimate pathway that is in plants and some microorganisms. Glyphosate can affect bacterial symbionts of animals that reside near agricultural sites, such as bees. The honey bee gut microbiota has eight bacterial species that encourage weight gain and reduce susceptibility to pathogens.

The gene encoding EPSPS is in virtually all of the sequenced genomes of bee gut bacteria. This indicates they could be susceptible to glyphosate. The study demonstrated the relative and absolute abundances of dominant gut microbiota species are reduced in bees that were exposed to glyphosate at levels that are common in the environment. Glyphosate exposure of young worker bees increased the mortality of bees that were then exposed to the pathogen Serratia marcescens. Various bee gut microbiota varied in their degree of susceptibility to glyphosate, largely depending upon whether they had an EPSPS of class I (glyphosate sensitivity) or class II (glyphosate insensitivity).

The basis for sensitivity differences was determined using in vitro experiments where the EPSPS gene from bee gut bacteria was cloned into Eschericha colia. All of the strains of core bee gut species, Snodgrassella alvi, have a sensitive class I EPSPS, and reduction in S. alvi levels was a regular result of the experiment. But some S. alvi strains seems to possess a different mechanism of glyphosate resistance. So, exposure of bees to the chemical can disturb their beneficial gut microbiota. This can affect bee health and how effective they are as pollinators.

Study Conclusion

Honey bees rely on gut microbial community for many functions, including food processing, the regulation of their immune system and defense against a variety of pathogens. Disturbances in this system have the possibility to cause negative consequences for fitness of the host. The study found that glyphosate affects bee gut microbiota composition and that bacterial strain and species in this community vary in the level of susceptibility to glyphosate.

Experimental and observational studies have provided strong evidence that dysbiosis that affects the bee gut can boost susceptibility to invasion by pathogens. Results also suggest that the development of a normal microbial community is important for protection against damaging pathogens of honey bees.

The study found that some species in bee guts can handle higher concentrations of glyphosate because of the presence of class II EPSPS enzyme. But others are more sensitive to the presence of class I EPSPS. The steady presence of glyphosate on bee gut microbiota had a negative impact on the growth of S. alvi, which have a sensitive EPSPS.

But some strains of S. Alvi may be able to handle the presence of glyphosate via an as yet unknown mechanism. Because bee but symbionts affect bee nutrition, development defense against enemies, disturbances in these gut communities could be a factor to make bees more vulnerable to various environmental stressors, such as poor nutrition and pathogens.

Bees With Damaged Guts Die Faster

Bees with damaged gut microbiomes were more likely to die when they were exposed to the pathogen Serratia marcescens, compared with bees with normal guts. Serratia is a widespread pathogen that can infect bees all over the world. About 50% of bees with healthy microbiomes were still living eight days after they were exposed, while just 1/10 of bees whose microbiomes had been altered by exposure to Roundup were still living.

Moran noted that studies in bees, humans and other animals show that the gut microbiome is a normal and stable community that can resist infection by invading bacterial species. If you disrupt this stable community with a herbicide, the bee can be more susceptible to an invasion of dangerous pathogens.

Based on this research, the scientists recommend that landscapers, farmers, and homeowners do not spray Roundup on flowering plants that bees are most likely to visit.

More than 10 years ago, beekeepers in the US were alarmed to find their hives had been decimated by what is called colony collapse disorder. Millions of bees seemed to disappear mysteriously. This left farms with far fewer pollinators for their crops. Explanations for the problem have included exposure to antibiotics or pesticides, loss of habitat or bacterial infections. This newest study adds herbicides as a very likely factor in this disturbing trend.

The scientists note that this is not the only thing that is causing the deaths of bees, but Roundup is definitely involved. People should take note of it because glyphosate is used all over the place.

Also, native bumblebees have microbiomes that work similarly to honey bees, so it is likely that they would also be affected by glyphosate in the same way.

It also should be noted that glyphosate is not the only Monsanto ingredient leading to bee deaths. The company also markets seed treatment with neonicotioids. This is a class of insecticides that have been scientifically proven to kill bees and butterflies.

In 2013, the EU banned neonics from being used outdoors.

Bee Decline Could Worsen

The news that the weed killer could be damaging to bees has serious consequences when we consider that the bee population is already in decline. Many factors are being blamed for the decline, including parasites such as the varroa mite, farming methods that kill flowering plants, and insecticides such as neonicotinoids that directly harm bees.

Why We Need Bees

Bees are one of the major pollinators in the world and life as we know it would cease to exist without them. Without bees, many fruits and vegetables, most foods for babies and all prepared products that contain sunflower oil and personal hygiene products that have shea butter could not be produced.

Experts note that life on earth would basically collapse without insects. They are at the heart of all ecological processes. About ¾ of the crops that we grow benefit from insect pollination, which provides us with ⅓ of the foods we consume.

These include delicious fruits and vegetables, coffee and chocolate and more. Our diets would be much worse and less healthy without bees doing their work of pollination. Bees also are important for breaking down leaves, dead trees and dead animal bodies. They assist in recycling nutrients and make them available again.

If it were not for insects, cow manure and dead bodies of animals would pile up, so, scientists say, we should be very concerned about the decline in the bee population.

How to Save the Bees

According to Greenpeace, there are three commonsense actions that can protect the bees of the world:

  • Ban the seven most dangerous pesticides, including glyphosate.
  • Protect pollinator health by better preserving bees’ wild habitat.
  • Improve ecological agriculture

Greenpeace says restoring bee populations and making healthier bees will improve pollination and ecological agriculture, which will improve crop yields.

Monsanto Issues Denial

Of course, Monsanto denies that its product has any effects on bees.

A spokesperson stated in 2017 that claims that glyphosate has a negative effect on bees is not true. No large-scale study has found a link between glyphosate and the decline of the bee population. More than 40 years of scientific evidence shows that the herbicide does not pose a serious risk for humans, animals, and the environment.

However, the fact that Monsanto just lost a huge $289 million verdict to a man who got cancer from Roundup, evidence is piling up that glyphosate does great harm to both humans and animals. It is hardly a surprise that Monsanto and its parent company Bayer is circling the wagons to protect its shareholders’ profits.

References

Michael Bennett

Michael Bennett is Editor-in-Chief of WeedKillerCrisis. Since 1999, he's worked across a multitude of areas of consumer protection including defective products, environmental issues, identity theft, predatory lending and more.

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